Bloodspiller Rogue
Whether you're a street level thug or royally appointed assassin, you've learned how to make your targets bleed. Your fighting style can often be described like a viper - lashing out quickly, hitting hard, then backing off until your opponent bleeds out. Knowing the weak points of the body is your speciality, and while it might not be pleasant work it's what you're best at.
When you first choose this subclass you gain proficiency in the Medicine skill and the Poisoner's Kit. If you already have proficiency in these skills you may choose another. Your proficiency bonus is doubled for these skills.
At 3rd level, you become proficient in the two weapon fighting style. All normal rules for dual weapon fighting applies to this proficiency: your off-hand weapon must have the light feature. You can use a Bonus Action to make an attack with your off-hand weapon so long as you make an attack Action with your main-hand weapon. You can then add your proficiency bonus to your off-hand weapon attack.
Additionally at 3rd level, you gain access to a specialised poison known as bloodblossom. The bloodblossom flower appears similar to the red spider lily plant and only the most precise hands can harvest its toxin. During a long rest you may choose to harvest bloodblossom poison without losing the benefits of a long rest, however you do require a Poisoner's Kit in order to properly harvest it, and you have free vials equal to your proficiency bonus. Upon finishing the long rest you may choose how to process the toxin. The saving throw for your bloodblossom poison DC is equal to 8 + your Intelligence modifier + proficiency bonus. Upon initiating your next long rest any remaining toxin you have left from your previous harvest becomes inert and cannot be used.
Blade Venom - As a Bonus Action you can apply the poison to one weapon or one arrow. Upon successfully landing an attack, the target must make a Constitution saving throw or take 1d12 poison damage or half as much on a successful save. This can be stacked with sneak attack. The poison is then spent and you must wait until your next long rest to create more. The damage increases at 9th level to 2d12, and at 17th level to 3d12.
Toxin Vials - You synthesise your bloodblossom into several vials to be stored for later. You can make a number of vials equal to your proficiency bonus. These vials can then be emptied into a target's food or drink. Upon being consumed, the target must make a Constitution saving throw. If the target fails this saving throw they fall unconscious, and cannot be woken up for 1d4 hours. If the target critically fails this saving throw (rolling a 1 on the dice) they fall unconscious and immediately begin making death saving throws.
Blood Dust - You craft a poisonous mist from your bloodblossom that's stored inside small, easily broken apart grenades. You can craft a number of grenades equal to your proficiency bonus. Using a Bonus Action you can throw one of these grenades (30/60 range) to which it explodes in a 10 foot radius. Every creature caught in this explosion must make a Constitution saving throw. Upon failing the saving throw the targets have disadvantage against saving throws for one minute.
At 9th level you become a master at harvesting your bloodblossom. Upon completing a long rest in which you decide to harvest your bloodblossom toxin you can choose to change the damage type of your toxin to: poison, fire, cold, acid or necrotic. Upon changing your bloodblossom damage type you must wait until your next long rest to change it again.
At 13th level you master the technique of preventing your bloodblossom toxin from going to waste. You no longer lose your remaining unused toxin upon initiating a long rest. So long as you have enough vials to store the toxin (vials can be bought for 1 gold each) you are able to retain the active toxin indefinitely.
